statemachine.java

一种将c高级语言转化给VHDL的编译器

/*
 *
 LA-CC 05-135 Trident 0.7.1

Copyright Notice
Copyright 2006 (c) the Regents of the University of California.

This Software was produced under a U.S. Government contract
(W-7405-ENG-36) by Los Alamos National Laboratory, which is operated
by the University of California for the U.S. Department of Energy. The
U.S. Government is licensed to use, reproduce, and distribute this
Software. Permission is granted to the public to copy and use this
Software without charge, provided that this Notice and any statement
of authorship are reproduced on all copies. Neither the Government nor
the University makes any warranty, express or implied, or assumes any
liability or responsibility for the user of this Software.

 
 */ 
package fp.circuit;

import java.util.*;

import fp.util.BooleanEquation;
import fp.util.BooleanOp;
import fp.flowgraph.*;


public abstract class StateMachine {

  public static final String FSM_OUT = "o_s%";
  
  protected int _states;
  private int _start_state;

  protected BooleanEquation[][] _table;

  private HashMap _inputs;

  public StateMachine(int states) {
    _states = states;
    _start_state = states - 1;
    initTable();
    _inputs = new HashMap();

    // this must be done after the edges are setup
    //collectInputs();  // instead, do this in subclasses?
  }

  public int getStates() { return _states; }

  public int getStartState() { return _start_state; }
  void setStartState(int s) { _start_state = s; }

  public BooleanEquation[][] getTable() { return _table; }

  public HashMap getInputs() { return _inputs; }
  public void addInput(String a, Object o) { _inputs.put(a,o); }

  void initTable() {
    _table = new BooleanEquation[_states][_states];
    for(int i=0; i < _states; i++) {
      for(int j=0; j < _states; j++) {
	if(i == j-1)
	  _table[i][j] = new BooleanEquation(true);
	else if((i==_states-1) && (j==0)) {
	  BooleanOperand boolop = Operand.newBoolean("start");
	  _table[i][j] = new BooleanEquation(boolop, true);
	} else if((i==_states-1) && (j==_states-1)) {
	  BooleanOperand boolop = Operand.newBoolean("start");
	  _table[i][j] = new BooleanEquation(boolop, false);
	} else
	  _table[i][j] = new BooleanEquation(false);
      }
    }
  }

  void collectInputs() {
    for(int i=0; i < _states; i++) {
      for(int j=0; j < _states; j++) {
	BooleanEquation eq = _table[i][j];
	if (eq.isTrue() || eq.isFalse()) continue;
	LinkedList operands = eq.listBooleanOperands();
	for(ListIterator iter=operands.listIterator(); iter.hasNext();) {
	  BooleanOperand op = (BooleanOperand) iter.next();
	  // why hash both ??
	  addInput(op.getFullName(), op);
	}
      }
    }
  }

  public HashMap getExitConditions() {
    HashMap map = new HashMap();
    for(int i = 0; i < (_states-1); i++) 
      map.put(new Integer(i), _table[i][_states-1]);
    return map;
  }

  /**
   * Returns the predicate associated with the backedge pointing to the given 
   * block.  Null is returned if no backedge is found.
   */
  static BooleanEquation getBackEdge(BlockNode bn) {
    // For each outedge in bn...
    for(Iterator eIt = bn.getOutEdges().iterator(); eIt.hasNext(); ) {
      BlockEdge edge = (BlockEdge) eIt.next();
      // If this outedge points to this blocknode...
      if(((BlockNode)edge.getSink()).equals(bn))
	return edge.getPredicate();
    }
    return (BooleanEquation) null;
  }

  public String toString() {
    int cycles = _states;
    StringBuffer sbuf = new StringBuffer("State Transition Table\n");
    sbuf.append("From  :  -> to State\n");
    for (int i= 0;i<cycles;i++) {
      sbuf.append("Cycle : ");
      sbuf.append(Integer.toString(i)).append("      ");

      for(int j=0;j<cycles;j++) {
	sbuf.append(_table[i][j]).append(" ");
      }
      sbuf.append(";\n");
    }
    return sbuf.toString();
  }

}